Anostraca

---

Streptocephalus namibiensis(LC) is endemic to southern Africa, occurring in Botswana, South Africa and Namibia, where it is widespread, but mainly occupies temporary brackish pans. As with all anostracans, their taxonomic features are complex and are only visible under high magnification. Therefore accurate species identification requires specialised expertise. © Betsie Milne.

25%
of 36 assessed species are
Threatened

64%
of 36 species are assessed as
Least Concern

44%
species are
Endemic

---

Key findings

• There are 38 described Anostraca species in South Africa, representing ~11% of the world’s species (~353)¹.

• A comprehensive assessment of 36 Anostraca species was conducted for the first time using the IUCN Red List Categories and Criteria to classify their risk of extinction (two species are still in review, which will take the total assessed species to 38).

• Of the assessed taxa, nine species (25%) were assessed as threatened with extinction, and of these, two species are considered Critically Endangered (Possibly Extinct) (Meyer-Milne et al. in prep).

• Endemism is high, with 44% (16) species only found in South Africa. Of these, 56% (9 species) are threatened with extinction, placing sole responsibility on South Africa to protect and conserve these species (Meyer-Milne et al. in prep).

• This assessment of Anostraca contributed to 58% of the global Anostraca IUCN assessments, making a sizeable contribution to the understanding of the current state of these temporary freshwater habitat indicator species.

• The IUCN Red List Index (RLI) assessment revealed that Anostraca have the third lowest RLI score (0.84), making it one of the most threatened taxonomic groups in South Africa. This illustrates the need for further surveys of temporary freshwater systems in the country, to understand their drivers of threat better as well as guide efforts to prevent further losses.

• Major threats to Anostraca are habitat loss and degradation due to urban and agricultural expansion, and mining.

Threat status, trends and pressures

1. Threat status

add text

Figure

Figure 1. Threat status of South African …

Data

Table 1. Plant threat status.

Taxon	Critically Endangered (Possibly Extinct)	Endangered	Vulnerable	Near Threatened	Data Deficient	Least Concern	Total
Overall spiders	2	4	3	2	1	24	36
Endemic spiders	2	4	3	1	1	5	16

2. Trends (RLI)

add text

Figure 2. The Red List Index (RLI) for …

NoteBox 1. Species box

Box 1. Title

add text

remove the syntax “” for inserting the images replace existing with appropriate images for current page

3. Pressures

add text

Figure 3. Key pressures on South Africa’s …

NoteBox 2. Species box

Box 2. Title

Add text

remove the syntax “” for inserting the images replace existing with appropriate images for current page

Protection level

Main findings

Add text

Further analysis and main findings can be found on the Assessment Summary Statistics page

Monitoring

add text

Species recovery

NoteBox 3. Species box

Box 3. Title

Add text

remove the syntax “” for inserting the images replace existing with appropriate images for current page

Knowledge gaps

add text

Recommended citation

Milne, B., Bills, D., Meissenheimer, K., Van Der Colff, D., Hendricks, S.E., Monyeki, M.S., & Mlambo, M. 2025. Anostraca. National Biodiversity Assessment 2025. South African National Biodiversity Institute. http://nba.sanbi.org.za/.

References

1. Rogers, D.C. 2013. Anostraca catalogus (crustacea: branchiopoda. The Raffles Bulletin of Zoology 61: 525–546.